Combination sensor guidewire and methods of use

ABSTRACT

The present invention provides for an improved combination sensor tip that includes an ultrasound transducer and a pressure sensor both disposed at or in close proximity to the distal end of the combination sensor tip. The present invention also provides for an improved connector to couple a guide wire to a physiology monitor that reduces torsional resistance when maneuvering the guide wire.

RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication Ser. No. 60/613,847, entitled Improved Connector andCombined Miniature Pressure and Flow Sensor, filed Sep. 27, 2004 whichis incorporated herein by reference in its entirety for all purposes.

FIELD OF THE INVENTION

This invention relates to an ultra miniature combined pressure sensorand flow sensor, an apparatus using the same, and methods for using thesame. This invention also relates to an improved connector forconnecting a guide wire to a monitor. This invention is particularlysuitable for making pressure measurements in coronary arteries of humanbeings.

BACKGROUND

It has been well known that it is desirable to make pressuremeasurements in vessels and particularly in coronary arteries with theadvent of angioplasty. Typically in the past, such pressure measurementshave been made by measuring the pressure at a proximal extremity of alumen provided in a catheter advanced into the coronary artery ofinterest. Such an approach has, however, been less efficacious as thediameters of the catheters became smaller with the need to advance thecatheter into smaller vessels and to the distal side of atheroscleroticlesions. This made necessary the use of smaller lumens that gave lessaccurate pressure measurements and in the smallest cathetersnecessitated the elimination of such a pressure lumen entirely.Furthermore, the catheter is large enough to significantly interferewith the blood flow and damp the pressure resulting in an inaccuratepressure measurement. In an attempt to overcome these difficulties,ultra miniature pressure sensors have been proposed for use on thedistal extremities of a guidewire. Using a guidewire with a smallerdiameter is less disruptive to the blood flow and thus provides anaccurate pressure reading. Currently, the use of two sensors on thedistal region of a guide wire has been proposed, such as, e.g., the useof flow sensor, for example, an ultrasound transducer or Doppler flowsensor, disposed near the distal tip of the guide wire in conjunctionwith a pressure sensor located proximally from the ultrasoundtransducer.

The current designs require a separation between the ultrasoundtransducer and the pressure sensor, which for some designs may beapproximately 3 cm. As a result, the current designs do not allow a userto take both Doppler flow measurements using the ultrasound transducerand pressure measurements using the pressure sensor at substantially thesame time at the same location, or to take both measurements near thedistal tip of the guide wire. For example, because the pressure sensoris located proximal from the ultrasound transducer, the currentlyproposed designs require a user to advance the guide wire to a desiredlocation, obtain a Doppler flow measurement with the ultrasoundtransducer, and then advance the guide wire further distally in order toobtain a pressure measurement using the pressure sensor at the samelocation. The additional distal movement of the guide wire using thecurrent designs is undesirable as such movement may inflict trauma (orfurther trauma) to the body, such as, e.g., to the arterial walls.Another disadvantage of the separated placement of the ultrasoundtransducer and the pressure sensor on currently proposed designs is thatthere may be a limit as to how far distally a measurement may be takenwith the guide wire. For example, the currently proposed designs are notable to take a measurement at the extreme distal end of a cavity or bodylumen because there is no room to maneuver the pressure sensor distallyto the desired location once the distal end of the guide wire is inphysical contact with the distal end of the body lumen. Also, whenattempting to advance one sensor to the location at which a measurementwas already taken with the other sensor, it is difficult to know theexact location to stop the advancement. It has not, however, beenfeasible prior to the present invention to provide for two differentsensors, such as, e.g., both an ultrasound transducer and a pressuresensor, in close proximity to each other near the distal tip of a guidewire. There is therefore a need for a new and improved ultra miniaturepressure and flow sensor, as well as a guide wire and apparatus forutilizing the same.

In order to provide measurement data to a user, the guide wire must becoupled to a physiology monitor located at the user's end.Unfortunately, the current methods for coupling and decoupling the guidewire directly to the physiology monitor or to a cable leading to thephysiology monitor are deficient in certain respects.

For example, the guide wire comprises basically a core wire and aplurality of electrical conductors disposed within an elongate tubularmember for transferring electrical signals from the sensors located atthe distal end of the guide wire. Usually three electrical conductorsare necessary for a stand alone pressure measurement guidewire and twoelectrical conductors are necessary for a stand alone flow sensorguidewire, thus in a combination guide pressure and flow measurementguidewire, five electrical conductors are required. These electricalconductors extend through the lumen from the pressure and flow sensorsat the distal end of the tubular member to a male connector located atthe proximal end of the guidewire for electrically and mechanicallyconnecting to a female connector, for example on a physiology monitor ora cable. During connection, there is a substantial risk that theproximal end of the guidewire and/or male connector may be bent and theelectrical connections may be damaged. Thus it is desired that theproximal portion of the guidewire is as stiff as possible forpushability, handling, kink resistance and catheter support. It is alsodesirable that the male connector portion is as stiff as possible to aidin the attachment and detachment of the male connector to the femaleconnector/cable. In traditional guide wires, the electrical conductorsextend in the space between a stainless steel core wire and the outerelongate tubular member, usually stainless steel. The stiffness of theguidewire is due for the most part to the dimensional and materialproperties of the core wire and the tubular member, specificallydiameter and thickness of the core wire and tubular walls. However,these properties are limited by the need to electrically insulate theelectrical conductors and to ensure that the electrical conductors haveenough space to freely extend without damage. The use of five electricalconductors in a combination pressure and flow sensor guidewire, insteadof the traditional two or three conductors for stand alone flow orpressure sensor guidewires, further complicates the solution.

Additionally, the use of traditional rotary connectors to connect theguidewire to the physiology monitor may render the guide wire awkward tomanipulate and often require high insertion forces to place the guidewire in the connector. These traditional connectors also exhibit a highdegree of torsional resistance, which also increases the difficulty ofmanipulating the guide wire within the body.

In general it is an object of the present invention to provide an ultraminiature pressure sensor, ultrasound transducer and guide wire andapparatus utilizing the same, making possible pressure and velocitymeasurements using a pressure sensor and an ultrasound transducerlocated in close proximity to each other on or near the distal end ofthe guide wire.

Another object of the present invention is to provide for increasedstiffness in the proximal end of the guidewire to increase the cathetersupport, handling, kink resistance and pushability of the guidewire anddecrease the risk of bending the proximal end of the guidewire ordamaging the electrical connectors inside of the guidewire.

Another object of the present invention is to provide for improvedmethods for coupling a guide wire to a physiology monitor or cable thatincrease the ease of connecting the guide wire to the monitor as well asincrease the ease of manipulating the guide wire within the body.

Additional features and objects of the invention will appear from thefollowing description in which the preferred embodiments are set forthin detail in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

The present invention provides for combination sensor tip which may besecured to the distal end of a guidewire having an ultra miniaturepressure sensor and an ultrasound transducer mounted on or near thedistal end of the combination sensor housing. In this embodiment, thepressure sensor and the ultrasound transducer are mounted in closeproximity to one another in order to enable pressure and flow velocitymeasurements to be taken at substantially the same time and location,and thus ensure a greater accuracy and consistency in the measurements.For example, the proximity of the pressure and flow sensors minimizesthe effect of side branch steal which can cause hemodynamic changes overshort segments. The close proximity of the sensors also increases theplacement accuracy of the sensors. Finally, the distal placement of thepressure sensor and ultrasound transducer on the combination tipincreases how far the sensors may be advanced within the body.

The present invention also provides for a guidewire with an increasedtubular wall thickness and a larger diameter core wire. This embodimentprovides improved stiffness in the proximal section of the guidewire,making it more durable and resistant to kinking, while maintaining theability to insulate the electrical conductors and permitting them tofreely extend from the pressure sensor and ultrasound transducer insidethe guidewire without damage. In one embodiment, this increasedstiffness is achieved by using an elongate tubular member with athickened wall containing a groove for each electrical conductorextending the length of the tubular member. The electrical conductorsmay then be positioned in the grooves where they will still have spaceto freely extend the length of the cable. Since the conductors areresting partially inside the grooves, the thickness of the tubularmember walls may be increased without cutting onto the free space forthe electrical conductors. In an alternative embodiment, the stiff innercore wire may also be increased in diameter to further reinforce thestiffness of the guidewire. Alternatively, the guidewire may be createdout of a composite polyimide tube wherein the electrical conductor wiresmay be sandwiched between layers of the polyimide tube as it is beingformed. In this embodiment, the diameter of the stiff inner core wiremay also be increased since the wires are embedded in the polyimide tubeand no longer need the space between the tubular member and the innercore wire to freely extend. Furthermore, since the electrical conductorsare insulated by the polyimide layers, additional insulating materialbetween the electrical conductors and the steel inner core wire is nolonger necessary. Thus, the diameter of the inner core wire may be evenfurther enlarged.

The present invention also provides for an improved connector to couplea guide wire to a physiology monitor. The connector includes an outerhousing having an inner passage which further contains a stationarycontact housing for electrically connecting to the conductors of thecoupled guidewire and a rotatable bearing assembly for physicallyengaging the wire. In this embodiment, the bearing assembly of engagesthe wire and is able to freely spin while the connector housing and thecontact housing remain static. This spinning capability of the bearingassembly reduces torsional resistance between the guide wire and a cableor monitor to which it is connected, thereby allowing a user tomanipulate the guide wire using less torque than required with currentconnectors.

These and other objects and features of the present invention will beappreciated upon consideration of the following drawings and detaileddescription.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a prior art combination sensor wire.

FIG. 2 illustrates an embodiment of the combination sensor tip accordingto the present invention.

FIG. 3 illustrates an alternative view of a combination sensor tipaccording to the present invention.

FIG. 4 illustrates the connectors of the combination tip guidewireaccording to the present invention.

FIG. 5 illustrates an alternative view of the connectors of thecombination tip guidewire according to the present invention.

FIG. 6 illustrates a cross section of a prior art guidewire.

FIG. 7 illustrates a cross-section of an embodiment of the guidewireaccording to the present invention.

FIG. 7 a illustrates a cross-section of an embodiment of the guidewireaccording to the present invention.

FIG. 8 illustrates an embodiment of the guidewire according to thepresent invention.

FIG. 8 a illustrates an embodiment of the guidewire according to thepresent invention.

FIG. 9 illustrates an alternative embodiment of the guidewire accordingto the present invention.

FIG. 9 a illustrates a cross-section of the guidewire illustrated inFIG. 9 taken along the line a-a.

FIG. 9 b illustrates a longitudinal section of an alternative embodimentof the guidewire illustrated in FIG. 9 taken along the line B-B.

FIG. 10 illustrates a proximal end of an alternative embodiment of theguidewire according to the present invention.

FIG. 11 illustrates a proximal end of an alternative embodiment of theguidewire according to the present invention.

FIG. 12 illustrates an embodiment of the connector of the presentinvention.

FIG. 13 illustrates an expanded view of the connector of the presentinvention.

FIG. 14 illustrates a sectional expanded view of the connector of thepresent invention.

FIG. 15 illustrates an embodiment of the connector of the presentinvention.

FIG. 16 illustrates an embodiment of the connector of the presentinvention with the guidewire inserted.

FIG. 17 illustrates an embodiment of the flow guidewire contacts on thecontact housing according to the present invention

FIG. 18 illustrates an embodiment of the pressure guidewire contacts onthe contact housing according to the present invention

FIG. 19 illustrates an embodiment of the pressure and flow guidewirecontacts on the contact housing according to the present invention

FIG. 20 illustrates an embodiment of an alternative pressure sensorhousing according to the present invention.

FIG. 20 a illustrates a side view of a longitudinal cross section of thealternative pressure sensor housing illustrated in FIG. 20 taken alongthe line B-B according to the present invention.

FIG. 20 b illustrates a top view longitudinal cross section of analternative pressure sensor housing illustrated in FIG. 20 taken alongthe line B-B according to the present invention.

FIG. 20 c illustrates a cross-section of an alternative pressure sensorhousing illustrated in FIG. 20 taken along the line A-A according to thepresent invention.

FIG. 21 illustrates an alternative pressure sensor housing according tothe present invention.

DETAILED DESCRIPTION

Turning to FIGS. 2-3, a combination sensor tip 100 of the presentinvention is illustrated. The combination sensor tip 100 includes a flowsensor 101, for example an ultrasound transducer, a Doppler flow sensoror any other suitable flow sensor, disposed at or in close proximity tothe distal end 102 of the combination sensor tip 100. The ultrasoundtransducer 101 may be any suitable transducer, and may be mounted in thedistal end using any conventional method, including the manner describedin U.S. Pat. No. 5,125,137, which is fully incorporated herein byreference. Conductors (not shown) may be secured to the front and rearsides of the ultrasound transducer 101, and the conductors may extendinteriorly to the proximal extremity of a guide wire.

The combination sensor tip 100 also includes a pressure sensor 104 alsodisposed at or in close proximity to the distal end 102 of thecombination sensor tip 100. The pressure sensor 104 may be of the typedescribed in U.S. Pat. No. 6,106,476, which is fully incorporated hereinby reference. For example, the pressure sensor 104 may be comprised of acrystal semiconductor material having a recess therein and forming adiaphragm bordered by a rim. A reinforcing member may be bonded to thecrystal to reinforce the rim of the crystal, and may have a cavitytherein underlying the diaphragm and exposed to the diaphragm. Aresistor having opposite ends may be carried by the crystal and may havea portion thereof overlying a portion of the diaphragm. Leads may beconnected to opposite ends of the resistor and extend proximally withinthe guide wire. Additional details of suitable pressure sensors that maybe used as the pressure sensor 104 are described in U.S. Pat. No.6,106,476. U.S. Pat. No. 6,106,476 also describes suitable methods formounting the pressure sensor 104 within the combination sensor tip 100.In one embodiment, the pressure sensor 104 is oriented in a cantileveredposition within a sensor housing 103. For example, the sensor housing103 preferably includes a lumen surrounded by housing walls. When in acantilevered position, the pressure sensor 104 projects into the lumenof the sensor housing 103 without contacting the walls of the sensorhousing 103.

As depicted in FIGS. 2-3, the combination sensor tip 100 incorporates asensor housing 103 designed to enclose both the ultrasound transducer101 and the pressure sensor 104. One advantage of the sensor housing 103is that because the sensor housing 103 encloses both the ultrasoundtransducer 101 and the pressure sensor 104, the need for two separatehousings, i.e., one for an ultrasound transducer and one for a pressuresensor, is eliminated. Accordingly, the use of a common sensor housing103 for the ultrasound transducer 101 and the pressure sensor 104 makesthe combination sensor tip 100 easier to manufacture than currentdesigns.

Additionally, unlike prior art designs, such as shown in FIG. 1, thecombination sensor tip 100 of the present invention provides for boththe ultrasound transducer 101 and the pressure sensor 104 to be disposednear the distal end of the combination sensor tip 100. In contrast, asshown in FIG. 1, the prior art combination wire, the pressure sensor 4is secured in a pressure sensor housing 3 and the ultrasound transducer1 is then located on a screw tip 10 that is mounted to a coil on thedistal end of the pressure sensor housing 3. This design results in asignificant separation between the pressure sensor 4 and the ultrasoundtransducer 1 that may be in the range of 3.0 cm. The combination sensortip 100 of the present invention is advantageous over prior art designsbecause by having both the ultrasound transducer 101 and the pressuresensor 104 near its distal end, the combination sensor tip 100 iscapable of being positioned further distally in a vessel or the bodythan the prior art designs. Additionally, the combination sensor tip 100of the present invention, unlike the prior art, is also able to takemeasurements from the ultrasound transducer 101 and the pressure 104 atapproximately the same location and approximately the same time, therebyresulting in greater consistency of measurements, greater accuracy ofmeasurements, and greater accuracy of placement within the body.Furthermore, placement of both the ultrasound transducer 101 and thepressure sensor 104 near the distal end of the combination sensor tip100 increases overall flexibility in a guide wire that incorporates thecombination sensor tip 100. For example, a prior art guide wire thatincludes separate sensors, with the pressure sensor being locatedsubstantially proximal from the ultrasound transducer, has a longerrelatively rigid area that must be devoted to the pressure and flowsensors, i.e., the distance from the ultrasound transducer to thepressure sensor. The present invention, in contrast, substantiallyreduces or entirely eliminates the distance between the ultrasoundtransducer and the pressure sensor, thereby allowing for increasedflexibility across this length.

It should be noted that in an alternative embodiment of the combinationsensor tip 100 (not shown) both the ultrasound transducer 101 and thepressure sensor 104 may be offset from the distal end of the combinationsensor tip 100, such as, e.g., 1.5 cm to 3.0 cm from the distal end, butstill located in close proximity to each other relative to prior artdesigns. Thus, the aforementioned advantages over the prior art designare still achieved.

In an alternative embodiment, as depicted in FIGS. 20-21, the pressuresensor housing 300 includes a tubular member 306 having an opening 308on the outer wall in communication with the lumen and a tip 302. The tipis constructed of a solder ball. Alternatively a weld, braze, epoxy oradhesive can be used. As shown in FIG. 20 a, the lumen 310 of thehousing is counterbored so that the lumen 310 has a smaller innerdiameter at the proximal end of the tubular member 306. For example, thehousing may be constructed in the counterbore fashion with a 0.010″inner diameter at the proximal end 314 and a 0.012″ inner diameter atthe distal end 312. As shown in FIGS. 20 a-20 c, the pressure transducer304 is coaxially housed in the lumen 310. In addition, a flow sensor(not shown) may be placed in the sensor tip 302 instead of the weld,braze, epoxy or adhesive to provide a combo sensor tip.

The advantage of the counter bore is that the housing is easier to make.The transducer 304 is simply slid into place in the lumen 310 and bonded(adhesive or epoxy) where the sides meet the proximal 0.010″ innerdiameter 314. The distal 0.012″ inner diameter 312 allows enough roomfor the pressure sensitive section of the transducer to be free from anycontact with the housing. Because of the counterbored lumen, there is noledge that has to be made on the outer wall of the lumen, rather thepressure transducer communicates with the outside via an opening 308 inthe outer wall of lumen. This protects better against theatherosclerotic plaque from entering and interfering with the pressuretransducer. As shown in FIG. 20 c, there is enough room for the threeconductor wires 307 a-c and the flattened core wire 322 on one side ofthe pressure transducer 304. In an alternative embodiment, shown in FIG.21, the aforementioned pressure housing may be located between the 3 cmlong platinum tip coil and the 27 cm long stainless steel coil forcoupling the housing to the elongate tubular member of the guidewire. Inthis intermediate housing version, the flattened core wire 322 passescompletely through the housing 306 and is bonded at the tip (not shown)of the platinum coil.

As further shown in FIGS. 2-3, a radiopaque tip coil 105 is provided atthe proximal end of the combination sensor tip 100. The radiopaque tipcoil 105 is coupled to a proximal coil 106, and the proximal coil 106may be coupled to the elongate tubular member. Another improvement ofthe present invention over current designs that use separate pressuresensor and ultrasound transducer housings is that the present inventionprovides a smoother transition from the elongate tubular member to thecombination sensor tip 100, i.e., the connection between the radiopaquetip coil 105, the proximal coil 106, and the rest of the guide wire isoptimized relative to current designs. Specifically, the transition issmoother and more flexible because of the absence of the housing betweenthe radiopaque tip coil 105 and the proximal coil 106. Current designs,such as the prior art guide wire shown in FIG. 1, generally have a tipcoil 5 attached to a pressure sensor housing 3, which in turn isconnected to a proximal coil 6. The present invention eliminates orgreatly reduces the separation between the tip coil and the proximalcoil that is required in current devices. Suitable coils for use withthe present invention are described in U.S. Pat. No. 6,106,476.

As depicted in FIGS. 4-5, signals from the ultrasound transducer 101 andthe pressure sensor 104 may be carried by fine wire conductors 107passing through the guide wire to conductive bands 108 a-e near theproximal end 110 of the guide wire. Usually three electrical connectorsare necessary for a stand-alone pressure measurement guidewire and twoelectrical connectors are necessary for a stand-alone flow measurementguidewire. Thus, depicted in FIG. 4-5, a guide wire incorporating thecombination sensor tip 100 of the present invention includes fiveelectrical conductors 107 extending through the lumen of the guidewireand five conductive bands 108 a-e on the proximal end 110 of theguidewire. The conductive bands 108 a-e may be electrically isolatedfrom each other by means of epoxy 109 a-d. Alternatively, polyimidetubes may be used to isolate conductors from the conductive bands. Theconductive bands transmit the electrical signals from the conductors viaa mating connector (or contact housing as described herein with respectto a connector of the present invention) to an instrument, such as,e.g., a physiology monitor, that converts the signals into pressure andvelocity readings that are displayed to the user. In addition algorithmssuch as Coronary Flow Reserve (CFR) and Fractional Flow Reserve (FFR)are calculated.

In general, the guide wire of the present invention is comprised of aflexible elongate element having proximal and distal ends and a diameterof 0.018″ and less as disclosed in U.S. Pat. No. 5,125,137, U.S. Pat.No. 5,163,445, U.S. Pat. No. 5,174,295, U.S. Pat. No. 5,178,159, U.S.Pat. No. 5,226,421, U.S. Pat. No. 5,240,437 and U.S. Pat. No. 6,106,476,all of which are incorporated by reference herein.

As disclosed in the abovementioned patents, a suitable guide wire mayconsist of a flexible elongate element having proximal and distalextremities, and can be formed of a suitable material such as stainlesssteel, Nitinol, polyimide, PEEK or other metallic or polymeric materialshaving an outside diameter for example of 0.018″ or less and having asuitable wall thickness, such as, e.g., 0.001″ to 0.002″. This flexibleelongate element is conventionally called a hypotube. In one embodiment,the hypotube may have a length of 130 to 170 cm. Typically, such a guidewire may further include a stainless steel core wire extending from theproximal extremity to the distal extremity of the flexible elongateelement to provide the desired torsional properties to facilitatesteering of the guide wire in the vessel and to provide strength to theguidewire and prevent kinking.

In an alternative embodiment, for example where a smaller guide wire isdesired, the guide wires disclosed in the above mentioned patents may bemodified to provide for improved stiffness. For example, where a smallerguide wire is desired, the hypotube can have an exterior diameter of0.014″ or less. In such an embodiment, however, the ability to achieve asuitable stiffness of the guidewire becomes a challenge due to spaceconstraints imposed by the both the small outer diameter of the hypotubeand the restricted space in the lumen of the hypotube. The use of fiveelectrical conductor wires required for a combination pressure and flowsensor as opposed to either two or three wires required for theindividual sensor guide wires further increases the challenge.

FIG. 6 depicts the cross-section of a typical prior art guidewire. Inthe prior art, the electrical conductor wires 107 a-e extend in thespace between the stainless steel core wire 112 and the hypotube 114.The annular space between the core wire 112 and the hypotube 114 isfurther filled with an electrically insulative material 116 such asepoxy or adhesive. Here, the stiffness of the guidewire is due mainly tothe properties of the core wire 112 and the hypotube 114 and less so tothe properties of the electrical conductors 107 a-e and insulativematerial 116. Specifically, the stiffness of the core wire 112 isproportional to the fourth power of the diameter and the stiffness ofthe hypotube is proportional to the difference between the fourth powerof the outer diameter and the fourth power of the inner diameter. Thus,increasing the diameter of the core wire 112 or increasing the thicknessof hypotube 114 are two ways to increase the total stiffness of thecross section. However, space must still exist for the electricalconductors 107 a-e to freely extend without damage. Thus, constraints onouter diameter of the hypotube 114 limit the ability of the prior artdesigns to improve the stiffness of the guidewire.

FIG. 7 depicts a guidewire according to the present invention thatallows for increased stiffness while still allowing for the electricalconductors to extend freely. Here, the elongate tubular member 124 hasthickened walls which further contain a plurality of longitudinalrecesses, or grooves, 126 a-e disposed on the inner surface andextending the length of the tubular member 124. The wire conductors 107a-e may then be positioned in the grooves 126 a-e where they will stillhave space to freely extend the length of the cable. Since theconductors 107 a-e are resting partially inside the grooves, the wallthickness of the tubular member 124 may be increased without cuttingonto the necessary space for the wire conductors 107 a-e. In addition,the excess space also allows for the stiff inner core wire 122 to beincreased in diameter to further reinforce the stiffness of theguidewire. The remaining space between the conductors 107 a-e and thecore wire 122 is filled with insulative material 128.

FIG. 7 a depicts an alternative embodiment of the improved guidewire.Here, the elongate tubular member 124 has thickened walls which furthercontain a single longitudinal recess 129, instead of a plurality ofrecesses, disposed on the inner surface and extending the length of thetubular member 124. The single longitudinal recess 129 is operably sizedto house all the conductor wires 107 a-e with enough space to permitthem to extend freely the length of the elongate tubular member. Theremaining space between the conductors 107 a-e themselves and betweenthe conductors 107 a-e and the core wire 122 is filled with insulativematerial 128.

The following table shows an example of the increase in wall thicknessof the hypotube and core wire diameter a 0.014″ guidewire between theembodiments shown in FIGS. 6 and 7. Embodiment Embodiment Tubular memberouter diameter .014″ .014″ Tubular member inner diameter .010″ .008″Core Wire Diameter .005″ .007″ Electrical conductor diameter .0015″.0015″

The increase in stiffness of the core wire of FIG. 7 is equal to:(0.007″)⁴/(0.005″)⁴=3.8

Therefore, the core wire 122 of FIG. 7 is 3.8 times stiffer than thecore wire 112 of FIG. 6. The increase in stiffness of the tubular memberof FIG. 7 is equal to:((0.014″)⁴−(0.008″)⁴)/((0.014″)⁴−(0.010″) ⁴=1.2

Therefore, the tubular member 124 of FIG. 7 is 1.2 times stiffer thanthe tubular member 114 of FIG. 6, neglecting any minor effect from thegroove(s).

In an alternative embodiment (not shown), it is also possible toincorporate only the thickening of the hypotube wall, or only theincrease in the core wire diameter. Additionally, if only the wallthickness of the hypotube is increased, and the core wire diameter staysthe same, the thickness of the hypotube can be increased even more whilestill leaving space for the conductor wires and thus the increase ofstiffness resulting from the hypotube thickness becomes even greater.

Alternatively, as depicted in FIGS. 8-9 b, the guidewire may be createdout of a composite polyimide tube wherein the electrical conductor wires137 a-e may be sandwiched between layers of the polyimide tube 130 and134 as it is being formed. The process for making this tube is shown inFIGS. 8-9 b. The first polyimide layer(s) 130 are deposited over asacrificial mandrel (not shown) whose outer contours are similar to theinner diameter of the hypotube 124 of FIG. 7. FIG. 8 shows five separateinsulated wires 137 a-e wrapped around the first polymide layer(s) 130.Alternatively, the five wires may be supplied on the same flex circuit.Each of the wires in FIG. 8 has a conductive core 132 made from aconductive material, such as copper and an insulative coating 131 madefrom an insulative material, such as polyimide, fluoropolymer, PEBAX orother insulative materials. The wires 137 a-e are wrapped around thecircumference of the tubular form of the first polyimide layer(s) 130.As shown in to FIG. 9, final layer(s) of polyimide 134 are depositedover the first polyimide layer(s) 130 and the electrical conductor wires137 a-e. The resulting composite tube has an inner diameter of, forexample, 0.009″ and an outer diameter of 0.014″. Because the conductivewires are self-contained in the wall of the tube, and insulated fromeach other and from other metallic components by the polyimide layers,additional insulating material between the electrical conductors and thesteel inner core wire is no longer necessary. Thus, in this embodiment,the core wire diameter can now be increased to an even greater extent sothat it substantially fills the inner diameter of the composite tube,for example a 0.008″ diameter core wire may be placed down the innerdiameter of a composite tube with a 0.009″ inner diameter.

FIG. 9 a shows a cross section of FIG. 9 taken along line a-a. Here, theelectrical conductor wires 137 a-e are disposed between the polyimidelayers 130 and 134. FIG. 9 b depicts a longitudinal section of FIG. 9taken along line B-B, showing the electrical conductor wires 137 a-esandwiched between the polyimide layers 130 and 134 of the tubularelongate member. At distal end of the composite tube 160, the polyimidematerial is dissected away, and the conductive wires extend to thedistal end of the product, where they are attached to the respectivesensor, such as the pressure sensor or the ultrasound transducer.

The completion of the proximal end assembly, i.e. the male connector, isshown in FIGS. 10 and 11. In FIG. 10, polyimide material is removed byone of many methods familiar in the art, such as cutting, grinding,etching, ablating, burning and drilling. One preferred method is lasermachining. The polyimide is removed at a point 140 a-e (d and e notshown) for each of the five wires: for wire 137 a at removal point 140a, for wire 137 b at removal point 140 b, etc.

The termination of the male connector is performed by a metal depositionprocess at a proximal section 162 of the composite tube 160. An areamade up of intermediate areas 150 a, 150 b, 150 c and 150 d is maskedand metal is deposited at areas 130 a, 130 b, 130 c, 130 d and 130 e. Aprocess of this nature is described in U.S. Pat. No. 6,210,339,incorporated herein by reference in its entirety. The deposited metal(or any conductive material) permanently adheres or couples to theexposed conductive wires at points 140 a-e where the polyimide layerswere removed. After the masking material 150 a-d is removed, there arefive independent conductive stripes 130 a-e, each connected to adifferent respective electric wire. Because of the precision nature ofthe winding process as well as the masking and metal depositionprocesses, a male connector is made that is short in length, yet veryreliable, in mating with a female connector and cable. Any metallizingprocess is conceived here, including the metallizing of the entiresection 162, followed by the etching of the metal material at 150 a, 150b, 150 c and 150 d. Alternatively, conductive bands may be coupled tothe exposed ends of the electric wires instead of the metallizingprocess.

In use, the combination sensor tip 100 is mounted on the distalextremity of the guidewire. The guide wire with the combination sensortip 100 mounted thereon may then be used in connection with a patientlying on a table or a bed in a cath lab of a typical hospital in which acatheterization procedure such as for diagnosis or treatment is beingperformed on the patient. The guide wire may be used with an apparatus,such as a connector, that consists of a cable that connects the guidewire to an interface box. The interface box may be connected by anothercable to a control console that has incorporated as a part thereof avideo screen on which measurements are displayed, such as, e.g., awaveform displaying ECG measurements as well as representations of themeasurements being made by the combination sensor tip 100. The abilityto measure and compare both the pressure and velocity flow and create anindex of hyperemic stenosis resistance significantly improves thediagnostic accuracy of this ischemic testing. It has been shown thatdistal pressure and velocity measurements, particularly regarding thepressure drop-velocity relationship such as Fractional Flow reserve(FFR), Coronary flow reserve (CFR) and combined P-V curves, revealinformation about the stenosis severity. For example, in use, theguidewire may be advanced to a location on the distal side of thestenosis. The pressure and flow velocity may then be measured at a firstflow state. Then, the flow rate may be significantly increased, forexample by the use of drugs such as adenosine, and the pressure and flowmeasured in this second, hyperemic, flow state. The pressure and flowrelationships at these two flow states are then compared to assess theseverity of the stenosis and provide improved guidance for any coronaryinterventions. The ability to take the pressure and flow measurements atthe same location and same time with the combination tip sensor,improves the accuracy of these pressure-velocity loops and thereforeimproves the accuracy of the diagnostic information.

FIGS. 12-15 depict an improved connector used to couple the guide wirewith a combination sensor tip to a physiology monitor. The connector 200includes a nosepiece 202 coupled to a connector housing 206, with thenosepiece 202 being located on the distal end of the connector housing206 and when in use oriented towards the proximal end of a guide wire. Aretainer 203 is secured to a threaded shell 204 located on the distalend of the connector housing 206 by means of a setscrew 208. Theretainer 203 limits the rotation of the nosepiece 202 during operationbetween a locked and unlocked position. The connector housing 206 has aninner passage which further contains a stationary contact housing 207for electrically connecting to the conductors of the coupled guidewireand a rotatable collet/bearing assembly 205 for physically engaging thewire.

As shown on FIGS. 13-15, the collet/bearing assembly 205 furthercomprises a collet head 210 which can be shifted between an open andclosed position to alternately engage or disengage a guide wire, aspring 212 and collet housing 209 to facilitate shifting the collet headbetween the open and closed positions and a rotational bearing 211 whichpermits the collet/bearing assembly to freely rotate within theconnector housing 206. As disclosed in U.S. Pat. No. 5,348,481,incorporated herein by reference, the ability of the collet/bearingassembly 205 to freely spin within the connector housing 206 acts toreduce the stress on the guidewire joints during steering and handlingof the guide wire. For example, the free spinning nature of thecollet/bearing assembly 205 enables a user to maneuver the guide wirewith a reduced amount of torque relative to prior art connectors becausetorsional resistance is reduced as a result of the spinning movement ofthe collet/bearing assembly 205.

The contact housing 207 is located near the proximal end of theconnector 200. The contact housing further contains a plurality ofelectrical contacts 217 for connecting with the conductive bands on theproximal end of a guidewire. The contact housing 207 does not rotate asthe guidewire rotates. In addition, a connector cable 213 extendsproximally from the contact housing 207 through an end cap 214 locatedat the proximal end of the connector 200. The connector cable 213 isconfigured to be coupled with a cable leading to a physiology monitor.

In use, when the connector 200 is in an unlocked position, the nosepiece 202 is pressing down on the collet housing 209 and compressing thespring 212 thus allowing for expansion of the collet head 210 whichprovides an opening through which the guidewire may pass. As shown inFIG. 16, the guide wire 220 may then be inserted into the connector 200and passed through the collet/bearing assembly 205 and the multiplecontacts 217 of the contact housing 207 until the guidewire touches thebackplate 215 of the contact housing 207 and a positive stop is felt. Inthis position, the conductive bands on the proximal end of the guidewire are lined up with the multiple contacts 217 of the connectorhousing and are physically in contact with contacts 217 of the contacthousing 207.

FIG. 17 depicts a flow guidewire 222 with two conductive bands 227 a and227 b located on the proximal end of the guidewire 222. When inserted inthe connector 200, the conductive bands 227 a and 227 b on the flowsensor guidewire 222 make contact with a respective electrical contact217 a and 217 b in the contact housing 207. Similarly, FIG. 18 depicts astandalone pressure wire 232 with three conductive bands 237 a-b and238. When inserted in the connector 200, the conductive band 237 a makescontact with two electrical contacts 217 c-d, the conductive band 237 bmakes contact with two electrical contacts 217 e-f and the conductivecontact 238 is grounded via contact with 217 g. In FIG. 19, a combinedpressure and flow sensor guidewire wherein the flow sensor conductivebands 217 a-b are each in contact with a single electrical contact 217a-b in the contact housing and the pressure sensor ground wire 238 is incontact with a single grounded contact 217 g, while the pressure sensorconductive bands 237 a-b are each in contact with two electricalcontacts 217 c-d and 217 e-f for redundancy. This use of redundantcontacts 217 c-d and 217 e-f for the contact wires 237 a-b from thepressure sensor ensures a more reliable electrical contact between theguide wire and the connector 200 is produced because if one dynamiccontact fails at any point during rotation of the connector 200 withrespect to the contact housing 207, another redundant contact is alsoconnected to assure no lapses.

The guidewire may then be locked into place by turning the nosepiece 202to the locked position. When the nosepiece is moved to the lockedposition, the spring 212 in the collet/bearing assembly 205 is releasedcausing the collet housing 209 to compress the collet/head 210 andthereby engage the guidewire. Thus, the engaged guidewire will be ableto freely rotate with the collet/bearing assembly 205, however thelongitudinal position of the guidewire will remain fixed. This ensuresthat the conductive bands of the guidewire will remain in contact withtheir respective contacts 217 in the contact housing 207 despite therotational movement of the guidewire. The alignment of the electricalcontacts of the guidewire with at least two contacts in the contacthousing further ensures the reliability of electrical connection etweenthe guidewire and the contacts in the connector.

In one embodiment, turning the nosepiece 202 approximately a quarterturn locks the guide wire in place and turning the nosepiece 202approximately a quarter turn in the reverse direction unlocks the guidewire from the connector 200. This is achieved by using a left hand(reverse) thread. The reverse direction is used to allow the connectorto operate with clockwise attachment and counterclockwise detachment,thus ensuring the motion is intuitive to the user. A stop tab 216 on thenosepiece 202 is configured to contact the locked position 218 on theretainer 203 when the nosepiece 202 is locked, and thereby to providetactile feedback to the user indicating whether the connector 200 islocked or unlocked. Thus, the connector 200 of the present invention isrelatively simple to operate due to the uncomplicated manner of lockingand unlocking the guide wire by turning the nosepiece 202 approximatelyone quarter turn in either of two directions.

Although the foregoing invention has for the purposes of clarity andunderstanding, been described in some detail by way of illustration andexample, many variations and modifications will become apparent to thoseskilled in the art. It is therefore intended and expected that thecertain changes and modifications may be practiced which will still fallwithin the scope of the appended claims. What is claimed is:

1. A combination sensor tip, comprising: a combination sensor housingfurther comprising an outer wall, and a distal end and a proximal end,having a lumen extending therebetween, the sensor housing adapted to bedisposed near a distal end of a guide wire; a coil disposed proximallyfrom the sensor housing for securing to the guidewire; a pressure sensorsecured to the outer wall of the sensor housing; and a flow sensordisposed within the lumen of the housing towards the distal end of thehousing, and in close proximity to the pressure sensor.
 2. Thecombination sensor tip of claim 1, wherein the sensor housing furthercomprises a cutout and the pressure sensor is mounted in the cutout suchthat an outer surface of the pressure sensor is substantially flush withthe external wall of the sensor housing.
 3. The combination sensor tipof claim 2, wherein the pressure sensor is mounted in a cantileveredposition within the combination sensor housing.
 4. The combinationsensor tip of claim 1, wherein the pressure sensor further comprises adiaphragm.
 5. The combination sensor tip of claim 1, wherein thepressure sensor further comprises a semiconductor crystal.
 6. Thecombination sensor tip of claim 1, wherein the flow sensor is adapted tomeasure flow velocity at substantially the same location as the pressuresensor.
 7. The combination sensor tip of claim 1, wherein the flowsensor is disposed at the distal tip of the combination sensor housing.8. The combination sensor tip of claim 1, wherein the coil furthercomprises: a radiopaque tip coil coupled to a proximal end of thecombination sensor housing, and a proximal coil coupled to theradiopaque tip coil and configured for coupling to a guide wire.
 9. Aguide wire assembly, comprising: a flexible elongate member having aproximal end and a distal end, a lumen extending therebetween, and anouter wall; a core wire coaxially positioned in at least a portion ofthe lumen of elongate tubular member; a combination sensor housingcoupled to the distal end of the flexible elongate tubular member,having an outer wall and a distal end and a proximal end, and a lumenextending therebetween; a pressure sensor secured to the combinationsensor housing; a flow sensor disposed within the lumen of thecombination sensor housing towards the distal end of the housing,wherein the pressure sensor and the flow sensor are located in closeproximity to each other; a plurality of electrical connectors extendinglongitudinally from the pressure sensor to substantially the proximalend of the flexible elongate member; and a plurality of electricalconnectors extending longitudinally from the flow sensor tosubstantially the proximal end of the flexible elongate member.
 10. Theguide wire assembly of claim 9, wherein the combination sensor housingfurther comprises a lumen and an inner wall, and the pressure sensorprojects into the lumen of the combination sensor housing withoutcontacting the walls of the combination sensor housing.
 11. The guidewire assembly of claim 9, wherein the pressure sensor comprises asemiconductor crystal.
 12. The guide wire assembly of claim 9, whereinthe elongate tubular member further comprises a longitudinal recessdisposed on the indoluminal surface of the tubular member and extendingthe length of the tubular member, and wherein at least one of theplurality of electrical connectors from the flow sensor and the pressuresensor are positioned within the longitudinal recess.
 13. The guide wireassembly of claim 12, wherein the elongate tubular member furthercomprises a plurality of longitudinal recesses disposed on theindoluminal surface of the tubular member and extending the length ofthe tubular member, and wherein the plurality of electrical connectorsfrom the flow sensor and the pressure sensor are individually positionedwithin a separate longitudinal recess.
 14. The guide wire assembly ofclaim 12, wherein an insulating material is disposed between theelectrical conductors and the core wire.
 15. The guide wire assembly ofclaim 14, wherein the outer diameter of the core wire is substantiallythe same size as the inner diameter of the flexible elongate member. 16.The guide wire assembly of claim 9, wherein the flexible elongatetubular member further comprises a plurality of coaxial polyimidelayers, and wherein the plurality of electrical connectors for thepressure sensor and the ultrasound transducer are embedded between thepolyimide layers of the flexible elongate tubular member.
 17. The guidewire assembly of claim 16, wherein the outer diameter of the core wireis substantially the same size as the inner diameter of the flexibleelongate member.
 18. A guide wire assembly, comprising: a flexibleelongate member having a proximal end and a distal end, a lumenextending therebetween, and an outer wall wherein the elongate tubularmember further includes a longitudinal recess disposed on theindoluminal surface of the outer wall and extending the length of thetubular member for housing one or more electrical conductor wirescoaxially positioned in the lumen of the elongate tubular member; and acore wire coaxially positioned in at least a portion of the lumen ofelongate tubular member.
 19. The guide wire assembly of claim 18,wherein the elongate tubular member further comprises a plurality oflongitudinal recesses disposed on the indoluminal surface of the tubularmember and extending the length of the tubular member, for individuallyhousing a plurality of electrical connectors coaxially positioned in thelumen of the elongate tubular member.
 20. The guide wire assembly ofclaim 18, wherein the outer diameter of the core wire is substantiallythe same size as the inner diameter of the elongate tubular member. 21.A method for measuring the blood pressure and velocity at a targetregion within a patient's vasculature, comprising the steps of:introducing a combination sensor housing into the patient's vasculature,wherein the combination sensor housing has a pressure sensor secured tothe housing and an ultrasonic transducer disposed near the distal end ofthe housing, and wherein the pressure sensor and ultrasonic transducerare in close proximity; advancing the combination sensor housing to thetarget region within the patient's vasculature; obtaining measurementsfrom the pressure sensor; simultaneously obtaining measurements from theultrasonic transducer; and analyzing the measurements from the pressuresensor and the measurements from the ultrasonic transducer to determinethe pressure and flow velocity at the target region.
 22. The method ofclaim 21, further comprising: providing a control console, wherein theobtaining measurements from the pressure sensor, obtaining measurementsfrom the ultrasonic transducer and analyzing the measurements steps areperformed with the control console.
 23. The method of claim 21, whereinthe target region comprises a vascular stenosis.
 24. The method of claim23, further comprising: measuring the blood pressure and velocity on thedistal side of the stenosis in a first flow state; measuring the bloodpressure and velocity on the distal side of the stenosis in a secondflow state; and comparing the measurements to determine a severity ofthe stenosis.
 25. A guide wire connector, comprising: a housing having adistal end, a proximal end, and an internal passage therebetween; anosepiece having an opening therein that communicates with the internalpassage in the housing and has a thread to manipulate the housing formovement between a locked position and an unlocked position, whereinwhen the nosepiece is in the unlocked position the guide wire isinsertable into the connector, and when the nosepiece is in the lockedposition the guide wire is securely engaged by the connector; acollet/bearing assembly disposed within the internal passage of thehousing, proximal to the nosepiece, the assembly being configured toengage the guide wire, wherein the collet/bearing assembly still permitsrotation of the guide wire while the guide wire is coupled to theconnector; and a contact housing disposed within the internal passage ofthe housing, comprising one or more electrical contacts that communicatewith one or more conductive bands on a guide wire.
 26. The guide wireconnector of claim 25, further comprising a retainer coupled to anosepiece and to the housing, the retainer being configured to limitrotation of the nosepiece, wherein the nosepiece further comprises astop tab that engages the retainer when in the locked position.
 27. Theguide wire connector of claim 25, wherein the contact housing is locatedat a proximal region of the internal passage of the housing.
 28. Theguide wire connector of claim 25, wherein in the unlocked position theguide wire is insertable into the collet/bearing assembly, and in thelocked position the collet/bearing assembly fixedly engages the guidewire.
 29. The guide wire connector of claim 25, wherein thecollet/bearing assembly rotates relative to the internal passage of thehousing as the guide wire rotates.
 30. The guide wire connector of claim25, wherein the contact housing is fixedly secured to the internalpassage of the housing.